Sanding machine



June 8, 1965 H. w. MARTIN 3,187,472

sANDING MACHINE Filed July 5. 1962 4 Sheets-Sheet l AH 1 1 1 l l l l 4 1 l l l I\| Il.. I. @y -HLFQ -L 9 Y\ m 5 a [rn w, UV

H. W. MARTIN SANDING MACHINE June 8, 1965 4 Sheets-Sheet 2 Filed July 5, 1962 INVENTOR HAROLD W. MARTIN H. W. MARTIN SANDING MACHINE June 8, 1965 4 Sheets-Sheet 5 Filed July 5, 1962 INVENTOR HAROLD W. MARTIN 4 Sheets-Sheet 4 INVENTOR HAROLD W. MARTIN B 5k? ZM June 8, 1965 Filed July 5, 1962 United States Patent O 3,187,472 SANDING MACHHNE Harold W. Martin, Shelby, Ohio, assigner to American lJVIachine & Foundry Company, a corporation of New ersey Filed July 5, 1962, Ser.. No. 207,502 8 Claims. (Cl.- 51-174) This invention relates to sanding machines, and more particularly to the levelling mechanism in a machine of the type used where perfectly horizontal sanding is a critical requirement. Y

. The invention will be described in its application to a machine for sanding bowling lanes, because it is in such sanding lthat uniformity in a horizontal plane perhaps reaches its greatest importance. However, the invention is also applicable to other surface finishing operations of a similar nature. In the sport of bowling, the surface condition of a lane is a highly significant factor entering into movement of a ball toward the target area.

In order to be approved for oliicial play by the various bowling associations, one requirement that is imposed is that each lane must be level from side to side within close tolerances. Bowling lanes periodically must be given a complete refinishing and in the sanding operation it obviously is desirable to maintain a levelling control over the machine in order that trueness of the lanes will be maintained. Otherwise, the errors produced by uneven sanding can become cumulative until finally a lane deviates considerably from a horizontal plane.

One approach to levelling control has been to provide means which sense the degree of trueness of the lane and to regulate the cutting action accordingly. As a sanding machine proceeds along the lane it is necessary to detect even slight deviations from level and responsively to effect the necessary corrective adjustments as quickly as possible. Highly satisfactory sanding of Va lane can be accomplished only by the early detection of very small 'deviations and, ideally by the continuous initiation of correspondingly small corrective adjustments.

The main object of the invention is to provide an improved mechanism for regulating the cutting action in response to sensing means of the type mentioned. A highly accurate and suitable system for sensing the horizontal trueness of cutting is disclosed in the copending application of David C. Sams and Richard D. Walsh, Serial No. 207,501, filed July 5, 1962, and entitled Levelling System for Bowling Lane Sanding Machine. In a sanding machine, however, the optimum performance in achieving horizontal trueness will not be obtained unless the high quality of the sensing system is matched by the quality of the mechanism which acts in' response thereto to put into effect theactual corrective adjustments as needed. In accordance with the invention the levelling mechanism is highly positive in its action and is ideally suited for the application of very tine levelling adjustments. Briefly, in the disclosed embodiment of this invention the assembly which is responsible for effecting such corrective adjustments is pivotally mounted on a Y horizontal axis extending centrally Ithrough the assembly. In the illustrated case this assembly includes the cutting or pressure drum, and its pivotal mounting is in the nature of a trunnion. By virtue of lthis arrangement there is afforded in effect a single pointof adjustment, represented by the pivot axis, in comparison to complex and less dependable arrangements wherein corrective adjustments originate from mechanisms at separate points. As will be seen hereafter, the assembly including the drum is pivotally adjusted in a highly positive, accurate and dependable manner by a cam assembly controlled and operated in response to an electronic level sensing system.

a gear reduction unit 46, and which also serveY to drivejA Patented .lune 8, 1965 ice Other objects and advantages also will appear from the following description, read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevation of an entire bowling lane sanding machine in which the present invention is embodied; t y

FIGURE 2 is a partial plan view of the sanding roller assembly;

FIGURE 3 is a side elevation of the structure taken as indicated by lines 3 3 in FIGURE 2;

FIGURE 4 is a sectional side elevation taken as indicated by `lines 4 4 in FIGURE 2, but with the platten removed from beneath the pressure drum;

FIGURE 5 is a sectional end elevation taken as indicated by lines 5-5 in FIGURE 4; and

FIGURE 6 is a schematic illustration of the bubble type liquid levels and the electrical control system.

FIGURES 1 and 2 present top and side views of an entire sanding machine, although as previously indicated this invention concerns principally the mechanical levelling of certain machine parts-the sanding pressure drum in the instant case-to vmaintain trueness of a bowling lane or other iioor surface. In the particular machine illustrated, three drums are involved, namely, a driving drum 2, a cutting or pressure drum 4 and an idler drum 6. A suitable endless abrasive belt 8 of a width suiiicient to cover the full width of a bowling lane (typically 41 to 42 inches) is trained about these drums, and is rotated in a clockwise direction (in FIGURE 1) by means referred to hereafter. It is to be noted that :this sanding machine is of the type wherein the sanding belt travels in alignment with -the length of the bowling lane as distinguished from belt travel at a right angle to the lane.

The machine frame consists essentially of two parts. Forwardly, the machine frame is a weldment comprising spaced sidevmembers 10 and 12 spanned by cross members 14, 16 and 18. At the left-hand side of the machine the member 12 is detachably connected to the front cross member 18 by a pivotally connected plate 20 which is secured to the member 12 by special intermeshing elements (not shown) and athumb screw 22. The rearward machine frame is a weldment comprising spaced side members 24 spanned by cross members 34, 36 and 38. The left-hand side frame members 12 and 28 are detachably connected by a plate 30 and thumb screws' 32. The purpose of these detachable connections is, that by removing rearward plate 30 and swinging away forward plate 20 the side frame is broken at these locations to permit sanding belts to be slipped on and olf the drums 2, 4,

and 6. In the course of this operation the forward portion of the sanding machine is raised above the lane or `other iioor surface (by, means described hereafter) and to prevent the dropping of the then broken left-hand side there is incorporated a feature which is described in the copending application of John Zuercher, Serial No. 207,503, filed Iuly 5 17962, now Patent No. 3,123,944,

`and entitled Frame Structure for Sanding Machine.

The forward machine frame is cantilevered outwardly from the rearward machine frame, the raising and lowering of the forward machine frame relative to the bowling lane or other floor surface being 'effective to vary the cutting pressure.` The rearward machine frame is supportedpartly by heavy wheels 40 which'are keyed to a transverse axle 42 driven by an electric motor 44 through the machine operators controls.

the sanding machine along the bowling lane or other iloor surface. The remaining support for the sanding machine is provided by caster wheels 4S pivotally carried by a lead screw 50 which is axially adjustable by its rotation Within a stationary nut assembly 52. A frame 56 extending upwardly provides handle bars and a support for The. lead screw 50 is rotated to raise and lower the rear of the machine relative to the caster wheels 4S, thereby to raise and lower the cantilevered forward pressure drum 4 by rotation about the axis of axle 42, lead screw 50 is rotated by means of a universal drive shaft 54 which is manually operated by a hand wheel 58. It will be understood that by the operation of hand wheel 53 the pressure drum 4 may be raised completely above the floor surface (e.g. for the purpose of changing sanding belts) or on the other hand'may be lowered to apply light or heavy pressure to the floor surface being sanded.

In the course of movement of the sanding machine along a bowling lane the machine is maintained in parallel, centered relation to the lane by rollers 59 which ride along the division boards or other structure separating adjacent bowling lanes.

The finish which is removed from the floor surface in the form of dust is delivered to a closed dust container 60 by centrifugal blowers 62 which are connected to a collector duct 66 by ducts 68. A fire extinguishing system is provided which is the subject matter of the copending application of Arthur B. Viescas, Serial No. 207,504, iiled July 5, 1962, now Patent No. 3,146,558, and entitled Fire Extinguishing System for Sanding Machine. Briefly, this system comprises a tank 72 containing an approved tire extinguishing agent (such as carbon dioxide) which is connected by a line 74 to intake duct 76 of the dust container 60. A valve 75 is operated to admit the tire extinguishing agent to the dust container 60in response to asignal emitted by means (not shown) responsive to the temperature condition within the dust container.

The driving drum 2 is rotatably supported in bearings 78 and 80 at the side frame members 10 and 12, respectively. An electric motor 82 is mounted on a sub-frame assembly comprising cross members 83 and side members (not shown). Motor 82 drives a disk type clutch S6 through aV belt drive 84, the clutch 86 being engageable to drive an output shaft 8S which in turn is connected to the drum 2 by a belt drive 90. The engagement and disengagement of clutch 86 is effected through operation of a lever 92 by a control lever 94 at the machine operators position. Motor 82 also drives the previously mentioned centrifugal blowers through a belt drive 96.

Idler drum 6 is rotatably mounted at its left end by a bearing 102, and at its right end by an assembly generally designated 104. Assembly 104 is a pneumatically operating unit, the details of which need not be described -for purposes of the present invention. Brieiiy, however, the assembly 104-provides a bearing 105A which is cyclically shifted back and forth on a vertical line by Ithe very gradual reciprocable operation of a pneumatic motor 107. The resultant continuous shifting of the axis of drum 6causes a slight lateral movement of the belt 8' back and forth on the drums 2, 4 and 6. The purpose of suchbelt shifting is to produce a more uniform sanding of the bowling lane or other floor surface. The pneumatic motor 107 is responsive, in its reversals of movement, to a pneumatically operating nozzle and baffle unit 109 which senses the lateral shifting of the sanding belt 8.between predetermined limits. Y

At each side of the sanding machine a toggle structure 106 is provided to be used in moving the idler drum 6 backwardly, thereby to release the tension on the sanding belt 8 and adin its removal from the drums.

At the front of the sanding machine a vertically adjustable roller 108 is provided. This roller is so ad- 4 justed as to engage the fioor surface and thereby limit the bite of the cut only under unusual conditions.

The pressure drum 4 is rotatably supported by bearings mounted in a rectangular levelling frame comprising side plates 11?. and 114 and cross plates 116 and 11S. The levelling frame is mounted in the nature of a trunnion having the mutual axis of its pivots extending lengthwise through the machine and intermediate the left and right-hand sides thereof. These pivots are indicated at and 12.2., the fixed portions of the bearings being mounted on the frame cross members 16 and 14, respectively. It will be evident from the description that by virtue of this mounting of the levelling frame the pressure drum 4 supported therein can be maintained in exactly horizontal disposition despite deviations of the main machine frame from the horizontal because of unevenness of the bowling lane or other lloor surface being sanded.

Suspended by legs 123 depending from side frame plates 112 and 114 is a platen 125 which has a concave upper configuration conforming to the drum 4 and a at bottom surface. Between the belt S and this bottom surface there is provided a graphite-impregnated length of canvas 127. Platen 125 is used when making the iiner nishing passes across the floor surface, and when the platen is so used the drum 4 does not rotate but merely applies force thereto. When the preliminary rough cutting passes are being made the platen may be removed, as shown in FIGURE 4, and the drum 4 will then rotate. When platen 125 is not used the weight transmitted through drum 4 is applied to the lioor surface over a much smaller area than when the platen is used, and consequently the cutting pressure will be considerably greater in the former case. The rearward levelling frame cross plate 11S has at its left a cam track 124 which is inclined downwardly and centrally toward the right (in FIGURE 3) and a cam track 126 which is inclined downwardly and centrally toward the left. A lead screw 128 is freely journalled for rotation in a gear box 130 mounted on the frame member 12. A traveling nut 134 on lead screw 128 is joined with a carriage 136 having an upper roller 140, which rides flatly against a stationary member 142 forming an extension of the main machine framework, and having a lower roller 138 which straddles the cam track 124. Toward the right-hand side of the machine a second carriage 146 similarly has an upper roller 150 which rides against the member 142 and a lower roller 148 which straddles the cam track 126. Carriage 146 is connected to carriage 136 by a connecting link 144 and thereby a given movement of carriage 136 will result in an identical movement of the carriage 146.

A right angle bevel gearing unit 152 is constantly driven by an extension of the shaft of drum 2 and has a constantly rotating output shaft 154. A pair of normally free-wheeling electromagnetic clutches 156 and 158 are concentric with shaft 154. Within the gear box 130 there is a differential gearing generally indicated 160, through which the lead screw 128 may be rotated in either direction. Upon energization of clutch 158 the shaft 154 will drive the differential 160 through belt drive 162, and upon energization of clutch 156 the shaft 154 will drive differential 160 through belt drive 164. If magnetic clutch 158 is energized the lead screw 128 will rotate in a direction to move carriages 136 and 146 toward the right and if clutch 156 is energized the lead screw 128 will rotate in a direction to move carriages 136 and 146 toward the left in FIGURE 3. When the carriages 136 and 146 move toward the right, for example, the roller 148 will force the levelling frame plate 118 in a clockwise direction and thereby tend to lower the right-hand side while tending to correspondingly raise the left-hand side of drum 4. ergized, the drum 4 will maintain its position relative to the main machine frame. It will be understood that these angular adjustments of the drum 4 about1 the axis If neither of the clutches 156 and 158 is en-v of pivots 120 and 122 will be effected as necessary to maintain the axis of the drum in exactly horizontal disposition despite inclination of the main machine frame due to unevenness of the bowling lane or other oor surface. Thereby the floor surface will be sanded evenly, in a truely horizontal plane.

Mounted on the levelling frame side members 112 and 114, and subject to deviations thereof from horizontal position, is a beam 166. Beam 166 has depending legs 163 which are detachably connected to levelling frame extensions 17) by means of latches 172. It should be understood, therefore, that with respect to the horizontal the beam 166 will assume the same angularV relation as the axis of pressure drum 4. Afiixed to the beam 166 is `a pair of bubble type liquid levels or vials, indicated 174 and 176. These vials are identical, and each comprises a glass container having a slight upward curvatureV as in the case of any bubble type level. The vial-s 174 and 176 contain an electrically conductive liquid, preferably, methyl alcohol, and electrodes leading from within the vials to an electrical control circuit control the operation of this circuit in response .to level or non-level conditions of beam 166. The vial 176 will be referred to herein as the cut rightV vial because it operates to effect a corrective levelling adjustment when the right side of the bowling lane or other floor surface is sensed as being higher than the left side. The vial 174 will be referred to herein as the cut left vial because it operates in the opposite manner. As illustrated schematically, the vial 176 has embedded therein a tap or electrode 178 which is always immersed in the conductive liquid L and therefore is unaffected by movements of the bubble B. Protruding through the top of the vial 176, however, is a tap or electrode 180 which is insulated from the liquid L by the air gap in bubble B when the vial 176 is in perfectly level position, but which will be immersed in the liquid L if tilting causes the bubble B to move toward the right. In other words, if a voltage is applied across the electrodes 178 and 180 a signal current will not be conducted through the conductive liquid L and the electrodes when the vial 176 is level, but will be conducted when the bubble B shifts to the right by deviation of the vial 176 from the horizontal in a counterclockwise direction. Similarly, the vial 174 has a protruding tap or electrode 172 which is constantly immersed, and an upper tap or electrode 184 which is insulated from the conductive liquid L when the bubble B occupies the central, or level position. In this case, however, if the bubble B moves to the left due to a deviation of the vial 174 from the horizontal in a clockwise-direction, a signal current can then be conducted through the electrodes 182 and 184 via the conductive liquid L.

There is indicated in block-diagram form a Levelling Control System which comprises an electronic circuit that is controlled by the vials 174 and 176 and, in response thereto, operates the electromagnetic clutches 156 and 158. It will be understood that there are several types of systems available which can be used to operate and control the clutches 156 and 158. The illustrated arrangement, however, involving the two vials 174 and 176, has proved to be highly sensitive and accurate and also advantageous, in other respects. Various systems also may be devised to operate clutches 156 and 158'inv v1962 and entitled Levelling System for Bowling Lane Sanding Machine, towhich reference may-be made. Therefore, the Levelling Control System need not be described in detail herein. Briefly, the electronic system disclosed in the identified copending application comprises a pair of independently operating circuits, each of which is controlled by one of the ylevel-responsive vials.

These circuits have a pulse type of operation in that when either one of them is triggered a pulsating current is fed to one of the clutches. Therefore, the particular clutch involved undergoes discrete repetitive engagements until the pressure drum has been restored to an exactly level position.

In operation, as the sanding machine is driven along the bowling lane or other iloor surface by the wheels 4t) the horizontal attitude of the pressure drum 4 will be progressively inuenced by the trueness or unevenness of the lane. Obviously, however, it is desired to maintain the axis of the drum 4 in exactly a horizontal position despite the encountered unevenness of the lane. As unevenness of the lane is sensed by the vials 174 and 176 the Levelling Control System will operate the clutches 156 and 15S. If the left-hand side drops relative to the right-hand side of drum 4, vial 176 will signal Levelling Control System to energize electromagnetic clutch 158, which in turn will cause the rotation of lead screw in a direction to move carriages 136 and 146 toward the right-hand side of the machine. Such movement will cause the levelling frame which carries drum 4 to be rotated slightly about the axis of pivots and 122 until the vials 174 and 176 sense that the drum 4 has reached a truely horizontal position. If the right-hand side drops relative to the left-hand side of drum 4 the vial 174 will signal the Levelling Control System to energize electromagnetic clutch 156, which will cause lead screw 12S to drive carriages 136 and 146 toward the left-hand side of the machine. The levelling frame which carries drum 4 will then rotate in the 0pposite direction'about the axis of pivots 12) and 122 until the drum 4 again assumes a truely horizontal position.

From the above description it will be seen that the cam assembly for adjustment of the levelling frame affords a highly positive type of control. In effect, a singley means is provided for simultaneously adjusting both ends of the drum 4, and therefore there is no problem of coordinating the operations of separate means. of the trunnion type mounting of the levelling frame, i.e. about an axis extending longitudinally through the center of the machine, it is insured that the vertical adjustment 'of one end of the drum will be exactly matched by an opposite but equal adjustment at the other end of the drum. An additional advantage is that despite the ne degree of levelling control afforded, the structure for mounting and Y adjusting the drum is of sturdy yet simple construction.

It will be understood that although the invention has been shown as embodied in a machine particularly adapted to the sanding of a bowling lane, the invention is not limited in scope thereto and is applicable to analogous arts. Various departures from the specifically disclosed embodiment of the invention may be effected without departing from the scope thereof as defined by the following claims.

p intersecting the axis of said drum and in alignment with said line of travel, cam means operable on said frame to shift the same about the trunnion axis, and means responsive to the relationship of said drum axis to a tr-ue horizontal reference for operating said cam assembly to maintain trueness of cutting.

2. A sanding machine comprising a main machine frame, wheels on said frame for rolling travel of the machine along a straight line, a plurality of rotating parallel drums journalled cross-wise in said frame, an end- By Virtue less abrasive belt travelling about said drums, a member within said belt for applying pressure to the lower reach thereof along an active cutting area extending parallel` to said drums and transverse to said line of travel, means mounting said member in said frame for tilting movements about an axis transverse to the axes Vof said drums and midway between the ends thereof, thereby to control the trueness of cutting by said abrasive belt independently of any shifting of said drums relative to the frame, and means for sensing the relationship of said active cutting area to a true horizontal reference, and means responsive to said sensing means to shift said member about its said transverse axis and maintain trueness of cutting by said belt.

3. The invention according to claim 2, wherein said member comprises a drum, said means for mounting the same comprising a levelling frame in which the dmm is rotatably supported and a trunnion type mounting for said frame having a common pivot axis arranged transversely to and intersecting the axis of the drum.

4. A sanding machine comprising a main machine frame, means for supporting and driving said frame, a horizontal and rectangular levelling frame, a drum positioned within said levelling frame and rotatably journalled at opposite ends thereof, means pivotally mounting said levelling frame in said main frame on a horizontal pivot axis transverse to the axis of said drum, an endless abrasive belt trained about said drum, means for driving said belt with the lower portion thereof in its path of travel receiving backing support from said drum, and means operable on said levelling frame to shift the same about said pivot axis and thereby control the trueness of cutting by said belt in relation to a horizontal reference, the last-mentioned means comprising a cam assembly interconnecting the levelling frame and main frame, said cam assembly comprising relatively movable cam follower and inclined cam track members, one of said members being mounted on said levelling frame and the other of said members being mounted and driven from the main frame.

5. The invention according to claim 4, wherein said track member comprises a part of said levelling frame and said cam follower is carried by said main frame.

6. A sanding machine comprising a main machine frame, means for supporting and driving said frame, and an assembly supportedby said frame including an endless abrasive member and means for supporting and driving said abrasive member, said assembly comprising: a drum providing backing support for said abrasive member along an active cutting area thereof, a a levelling frame in which said drum is rotatably journalled, means pivotally mount'- ing said levelling frame in said main frame on a horizontal pivot axis transverse to the axis of said drum, said pivot axis crossing said drum approximately midway between the ends thereof, said levelling frame being thereby shiftable about said axis to control the trueness of cutting of said abrasive member relative to a horizontal reference, said levelling frame havingl a horizontal, rigid cross member extending transverse to said pivot axis at both sides thereof, said cross member having separate cam tracks at said opposite sides and inclined downwardly p at the same angle but in opposite directions, a pair of separate cam roller assemblies travelling on the respective cam tracks, a lead screw parallel to said cross member and laterally supported by said main frame, a travelling nut unit threaded on said lead screw and connected to said cam roller assemblies, and reversible means for rotating said lead screw to drive said cam rollers axially along the lead screw, thereby to maintain trueness of cutting by said abrasive member.

7. A sanding machine comprising a main machine frame, wheels on said frame for support thereof, means on said frame for driving of said wheels to propel the machine, and an assembly supported by said frame including an endless abrasive member and means for supporting and driving said member, said assembly comprising: a levelling frame extending across the width of said machine aligned bearings at the forward and rearward sides of said levelling frame and mounting the same in said main machine frame for tilting movements about a horizontal axis extending longitudinally relative to the machine, a single drum journalled in said levelling frame with its axis normal to said longitudinal axis, said drum providing backing support within said abrasive member along an active cutting area thereof, and the tilting of said levelling frame about said longitudinal axis being elfective to control the trueness of cutting of said member in relation to a horizontal reference, means for sensing the relationship of said cutting area to said horizontal reference, and means controlled by the last-mentioned means and operable on said levelling frame to maintain said truenessof cutting.

8. A sanding machine comprising a main machine frame, wheels on said frame for support thereof, means for driving of said Wheels to propel the machine, and an assembly supported by said frame including an endless abrasive member and means for supporting and driving said member, said assembly comprising a plurality of spaced parallel drums about which said abrasive member travels, said drums having parallel axes extending transverse to theV direction of travel of the machine, a levelling frame between said drums, bearing means at the forward and rearward sides of said levelling frame journalling the same for tilting movements about a horizontal longitudinal axis passing midway between the ends of said drums, a drum journalled in said levelling frame with its axis parallel to the axes of said other drums, the last-recited drum providing support for a cutting portion of said abrasive member, and means operable on said levelling frame to cause controlled shifting thereof about said longitudinal axis and thereby maintain trueness of cutting.

References Cited by the Examiner UNITED STATES PATENTS 963,481 7/10 Smith 51-174 1,804,523 5/31 Wolf et al 51-174 2,260,949 10/41 Mall 5 l-170.4 2,518,742 8/50 Armington I2806.1 X 2,598,080 5/52 Swalinkavich 51-174 2,688,217 9/54 Winkley et al 51-174 2,967,062 1/61 DAvigdor 280-112 LESTER M. SWINGLE, Primary Examiner.

J. SPENCER OVERHOLSER, FRANK E. BAILEY,

Examiners. 

1. A SANDING MACHINE COMPRISING A MAIN MACHINE FRAME, MEANS FOR SUPPORTING AND DRIVING SAID FRAME ALONG A FORWARD-REARWARD LINE OF TRAVEL, AN ENDLESS TRAVELLING ABRASIVE BELT, AND AN ASSEMBLY PROVIDING SUPPORT FOR A CUTTING PORTION OF SAID MEMBER COMPRISING: AN INNER DRUM PROVIDING A BACKING SUPPORT FOR THE LOWER REACH OF SAID BELT, A LEVELLING FRAME IN WHICH SAID DRUM IS ROTATABLY MOUNTED, A TRUNNION TYPE MOUNTING FOR SAID FRAME HAVING A PIVOT AXIS ARRANGED TRANSVERSELY TO AND INTERSECTING THE AXIS OF SAID DRUM AND IN ALIGNMENT WITH SAID LINE OF TRAVEL, CAM MEANS OPERABLE ON SAID FRAME TO SHIFT THE SAME ABOUT THE TRUNNION AXIS, AND MEANS RESPONSIVE TO THE RELATIONSHIP OF SAID DRUM AXIS TO A TRUE HORIZONTAL REFERENCE FOR OPERATING SAID CAM ASSEMBLY TO MAINTAIN SUCCESS OF CUTTING. 